Split-Gate TFT Structure for Shorter Channels in Display Panels
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Solution Overview
Problem
In thin film transistor (TFT) structures, the channel length is typically determined by the length of the top gate, which can lead to inefficiencies and instability in the threshold voltage due to hot carrier generation and resistance variations.
Innovation Solution
The proposed solution involves a thin film transistor structure with a gate that includes a first part to completely block doped ions over the channel and a second part to allow partial penetration of doped ions into the transition part, thereby narrowing the channel length and improving threshold voltage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the top gate is used as a mask to form the source and drain regions, then the manufacturing process is simplified, but the channel length cannot be narrowed and the threshold voltage becomes unstable
Solution Approach 1:
The gate is divided into two distinct parts: a first gate part and a second gate part. The first gate part serves as the mask during plasma treatment to form the source and drain regions, while the second gate part extends beyond the channel region to allow for channel length narrowing through additional plasma treatment. This segmentation enables independent optimization of both mask functionality and channel dimension control.
Solution Approach 2:
Different regions of the gate structure are given different functions: the first gate part (overlapping with the channel) provides masking during doping, while the second gate part (extending beyond the channel) enables precise channel length control. This local differentiation of function allows the same gate structure to simultaneously simplify manufacturing and improve threshold voltage stability.
2Device complexity
If the channel length is determined by the top gate length, then the device structure is simplified, but hot carrier generation increases and threshold voltage changes
Solution Approach 1:
The gate is segmented into a first gate part that defines the channel region and a second gate part that extends beyond it. This allows the channel length to be independently controlled by the second gate part's extension, enabling shorter channel lengths that reduce hot carrier generation while maintaining the overall simplified top-gate structure.
Solution Approach 2:
The gate structure is extended in the lateral dimension beyond the channel region. The second gate part protrudes beyond the channel edges, creating an additional dimensional element that enables precise channel length definition without complicating the vertical gate structure, thereby reducing hot carrier effects while maintaining structural simplicity.
3Reliability
If the LDD region is formed by contacting with silicon nitride film, then the resistance transition is achieved, but the channel length remains dependent on gate length
Solution Approach 1:
The gate is divided into first and second parts, where the second gate part extends beyond the channel region. This extension allows the channel length to be defined by the distance between the source/drain regions and the second gate part edges, rather than being constrained by the overall gate length. The LDD region formed by silicon nitride contact remains intact for resistance transition, while the channel length is now independently controllable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration allows for a narrower channel length and improved stability of the threshold voltage in TFTs, enhancing the overall performance and reliability of the thin film transistor structure.
Implementation Method 1
the first part may be disposed overlapping with the channel and used to block doped ions completely
Implementation Method 2
the second part may be disposed overlapping with the transition part and used to penetrate part of the doped ions
Data Source
AI summary
Embodiments of the present disclosure provide a driving substrate and a display panel, in which a transition part of an active layer is disposed between a first contact part and a channel of the active layer, a first part of a gate is disposed overlapping with the channel and used to block doped ions completely, a second part of the gate is disposed overlapping with the transition part and used to penetrate part of the doped ions; and a first electrode is connected to the first contact part, and a second electrode is connected to a second contact part.